The first time I went to Key West I toured this home (among other tourist things to do) and was thoroughly grossed out to learn that some of Hemingway's cats (well, the descendants of) had six toes. When we learned that, my sister and I were on a mission to find one of them (allergies notwithstanding) -- and we did.
But that's not really the point. The Hemingway house is your typical house-turned-museum: they roped off the rooms at the doorway and furnished the home with personal affects from Ernest himself -- furniture, photos, etc. It's a narrated tour from a guide that will answer any questions you may have about the house and Hemingway's life in Key West.
Aside from the six-toed cats, the only other thing that stuck out in my mind is that the house has the only basement in the city -- probably even the state, really.
The Hemingway House is a must-see stop for anyone visiting Key West. Here's the related http://www.hemingwayhome.com/ for more information.